In known computed tomography (CT) systems an x-ray source rotates around an object to be imaged, while the x-ray source emits x-rays and an x-ray detector detects the x-rays after having traversed the object, in order to generate projection values. The projection values are used for reconstructing an image of the object, wherein the reconstruction may include an iterative reconstruction procedure which is adapted to reconstruct the image by minimizing a cost function that depends on a quadratic difference between calculated projection values, which are determined by simulating a forward projection through the image, and the projection values that have been generated based on the detected x-rays.
The iterative reconstruction procedure can yield images of the object having a good quality, if the object is not moving and/or if the object has been completely illuminated by the x-rays. However, if the object is moving and/or if the object has not been illuminated completely, the quality of the reconstructed image may be reduced.
The article “Model based iterative reconstruction for Bright Field electron tomography” by Singanallur V. Venkatakrishnan et al., Proceedings of SPIE, volume 8657, pages 86570A-1 to 86570A-12 (2013) discloses an apparatus for acquiring Bright Field electron tomography (BF-ET) images using a Model based iterative reconstruction algorithm which accounts for the presents of anomalous measurements from Bragg scatter in the data during the iterative reconstruction. The method accounts for anomalies by formulating the reconstruction as minimizing a cost function which rejects measurements that deviate significantly from the typical Beer's law model assumed for BF-ET.